This invention relates to magnetic recording media, and more particularly, to an improvement in a topcoat film on magnetic recording media having a continuous thin film type magnetic layer.
In the field of magnetic recording media destined primarily for video and audio applications, active efforts have been concentrated on the development of magnetic recording media having a magnetic layer of continuous thin film type because of compactness of a roll of tape.
The preferred magnetic layers for such continuous thin film type media are films of Co, Co-Ni, Co-O, Co-Ni-O and the like deposited by the standard oblique evaporation technique wherein evaporation is effected at a predetermined angle with respect to a normal to the substrate.
Despite electromagnetic properties, the deposited magnetic layers have increased dynamic friction, low film strength, poor head contact, and in particular, low runnability or durability of tape during repeated passes, and thus produce a noticeable output drop after repeated passes. Poor corrosion resistance contributes to deterioration of many properties. In the case of video tape, the still life, that is, permissible still mode operation time is short. Many dropouts occur in the reproduction process.
To compensate for such drawbacks of deposited magnetic layers, it has been proposed to cover the layers with a variety of topcoat films. One example is a coated film of fluorocarbon resins. Prior art topcoat films of fluorocarbon resins, however, offer less satisfactory corrosion prevention and frequently produce head clogging.